Moodle in English

Moodle 1.9

Hi,
in my course I would make my students able to rate the solutions of the other students.
Therefore I gave the students, after they uploaded their solution in assignment-module, all the rights to see and rate the solutions of the others.
I do it in the assignment - there will be possibility to change the rights for it only within this assignment, not in the whole course.
They will be able to see the uploaded files in list an to rate, but not to open the files! After selection of any file a message occures: Access not allowed.

I think it must be a mistake, because what solution will they rate when they are not able to see them?

Any Ideas? Thanks
Peter